Grapevine canopy management can induce modifications in the grape and wine composition and quality, and summer pruning is among the cultural practices used to reach this objective. In this way, an experiment with different types of summer pruning were carried out to improve the quality of Merlot grape must. It was performed from 1993/1994 to 1996/1997 on a vineyard conducted in the pergola system. There were 12 treatments with three replications disposed in a randomized block design. Treatments consisted of control grapevines and 11 types of summer pruning, i.e., sprouting, topping and leaf removal, some of them applied in different times of the grapevine vegetative cycle. Results show that there was variation among years, but considering the average of the four vintages, the best treatments were 10 (sprouting + topping + leaf removal on the bloom time with removal of all leaves below clusters) and 9 (sprouting + leaf removal of half leaves below clusters 21 days before harvesting) proportioned higher synthesis and accumulation of sugar, expressed by ºBrix and density, and lower of acidity, expressed by tartaric and malic acids, pH and titratable acidity. Following in effectiveness, the treatments 11 (sprouting + topping + leaf removal of half leaves below clusters 21 days before harvesting), 2 (topping) and 3 (leaf removal of all leaves below clusters in the bloom time).
grapevine; Vitis vinifera; summer pruning; sprouting, topping; leaf removal
